Benzene, 2-hydroxy-3-methoxy

Interestingly, when carboxylate derivatives are considered, the SET process is irreversible (due to release of CO ) and the degradation rate is maximum when this mechanism is supposed to be operating. On the contrary, when a radical cation or a semiquinone intermediate is invoked, as in the case of quinoline or hydroxy-methoxy-chloro benzenes [60,64], the rate is minimum due to the back reaction. 

Synonyms Cerulignol Guaiacylpropane 1-(4-Hydroxy-3-methoxyphenyl) propane (4-Hydroxy-3-methoxyphenyl) propane 4-H y d roxy-3- m et h oxypro py I benzene 2-Methoxy-4-propylphenol 2-Methoxy-4-(1-propyl) phenol 2-Methoxy-4-n-propylphenol Phenol, 2-methoxy-4-propyl- 4-Propylguaiacol p-Propylguaiacol p-n-Propylguaiacol 4-Propylguaiacolcatechol 5-Propyl-o-hydroxyanisole 1-Propyl-3-methoxy-4-hydroxybenzene 4-Propyl-2-methoxyphenol... 

Elution with 1 2 ether-benzene solution gives 3)5-methoxy-7jS-hydroxy-B-homo-estr-5(10)-en-17-one (70a 1.52 g 77%) mp 105-115°. Two recrystallizations from benzene-petroleum ether give material having the following properties mp 118-120° [aj, 50.8° (CHCI3). 

Apparently the role of methanol is to intercept unstable species which otherwise tend to polymerize or rearrange. The methoxy peroxide (72) can be isolated in crystalline form if desired, but it is preferable to treat the methylene dichloride solution at 0° with zinc dust and acetic acid until the mixture shows a negative potassium iodide test. The resulting crude seco-aldehyde (73) is then cyclized to (74) by stirring with neutral alumina in benzene at room temperature for 3 hr. ° Wechter has recently reported a number of transformations of a 5yS-hydroxy-6yS-formyl-B-norpregnane prepared in 8% yield by photolysis and hydrolysis of a 5a-hydroxy-6 -azidopregnane. 

To a solution of vanillin in toluene is added nitroethane, butylamine and glacial acetic acid. The mixture is refluxed and the water of reaction is steadily azeotropically removed by distillation. After the theoretical amount of water is distilled out, distillation Is continued to remove excess reactants. The last trace of excess reactants is then removed at room temperature under a vacuum. The product is then triturated with a hydrocarbon solvent such as Skellysolve B and is thus obtained in a crystalline state. In general, however, it is preferred to dissolve the residue directly In toluene for use in the next step, without isolating the 1-(2-nitropropen-1-y I )-4-hydroxy-3-methoxy benzene. 

The solid residue obtained is recrystallized from a mixture (15 85) of benzene and cyclohexane and there is obtained 3-methoxy-10-[2-methyl-3-(4-hydroxy-1-piperidyl)-propyl]-phenthiazine (5.7 grams) as a white crystalline powder, MP 137°-13B°C. 

Dehydrogenation is a rarely used method for the production of fully unsaturated azepines, and there are no examples of its use for the formation of simple monocyclic systems, although 3-hydroxy- and 3-methoxy-2//-azepin-2-ones can be obtained by dehydrogenation of the corresponding l,5-dihydro-2//-azepin-2-ones with 2,3-dichloro-5,6-dicyano-l,4-benzoquinone (DDQ) in benzene in a sealed tube at 100 48-51-52-67... 

Cyclopropane, 1,1 -dibromo-2,2-diplienyl-[Benzene, l,l -(2,2-dibromocyclo-propylidene)bis-], 32 Cyclopropanecarboxyltc acid, 70 Cydopropanes, gem-dihalo, 32 CYCLOUNDECANONE, 107 Cycloundecanone, 2-hydroxy-, 110 Cycloundecene, 1-carboxy- [1-Cyclo-undecene-1-carboxylic acid], 111 Cycloundecene, 1-methoxy-, 111 1-Cycloundecene-l-carboxyhc acid, methyl ester, 108... 

The reaction of alkoxyarylcarbene complexes with alkynes mainly affords Dotz benzannulated [3C+2S+1C0] cycloadducts. However, uncommon reaction pathways of some alkoxyarylcarbene complexes in their reaction with alkynes leading to indene derivatives in a formal [3C+2S] cycloaddition process have been reported. For example, the reaction of methoxy(2,6-dimethylphenyl)chromium carbene complex with 1,2-diphenylacetylene at 100 °C gives rise to an unusual indene derivative where a sigmatropic 1,5-methyl shift is observed [60]. Moreover, a related (4-hydroxy-2,6-dimethylphenyl)carbene complex reacts in benzene at 100 °C with 3-hexyne to produce an indene derivative. However, the expected Dotz cycloadduct is obtained when the solvent is changed to acetonitrile [61] (Scheme 19). Also, Dotz et al. have shown that the introduction of an isocyanide ligand into the coordination sphere of the metal induces the preferential formation of indene derivatives [62]. 

No attention has been paid to numerous spectroscopic investigations which are concerned with the interaction between substituted aromatic substances and proton acids or Lewis acids, and from which no basicity gradations have been deduced. Reference should, however, be made to N.M.R. spectra of methoxy-benzenes in acid solutions, where a proton addition complex is formed (MacLean and Mackor, 1962 Brouwer et al., 1965a, b, c, d, e). In a summarizing treatment, Brouwer et al. (1965a) also quote pA values for various protonated hydroxy-... 

Hydroxy-B-methoxy-B-nitrostyrene. A solution of freshly distilled 2-hydroxy-3-methoxybenzaldehyde (5g), 2.5 ml of nitromethane and 2 g of ammonium acetate in 20 ml of glacial acetic acid is refluxed for two hours. Cool and pour the dark brown mixture into water and allow the gummy product to crystallize. Recrystallize from benzene with the acid of Norit. Yield 2.3 grams of yellow needles melting at 115-122°. This is also to be reduced to an active compound as described in JACS, 72, 2781. 

The difference in stability noted above is of the same order of magnitude as that found for the formation of adducts 22 and 23 for the reaction of 1,3,5-trinitrobenzene with the OH" and MeO" ions, respectively. Examination of the activation parameters shows some relevant differences between the heterocyclic and the homocyclic systems, however. The higher reverse rate for the methoxy adduct of trinitrobenzene 23 relative to the corresponding hydroxy adduct 22 is controlled by the higher activation entropy, whereas the higher reverse rate for the methoxy adduct of the dinitropyridine 1 relative to 3 is determined by the activation enthalpy. The entropy effect has been related to the different role of intramolecular interactions of the hydroxy adducts in the benzene and pyridine series. The reason for this difference is still unclear, however.45... 

Condensation of 7-methoxy-3,4-dihydro-1(2H)-naphthal-enone with tetramethylene dibromide by means of NaH in benzene or tert amyl alcohol gives 3,4-dihydro-7-methoxy-2,2-tetramethylene-1(2H)-naphthalene (bp (0,05 mbar) 120-123 °C), which is treated with acetonitrile and butyllithium in THF yielding 1-hydroxy-7-methoxy-1,2,3,4-tetrahydro-2,2-tetramethylene-1-naphthalene-acetonitrile (mp 140-142 °C). This compound is reduced with LiAIH4 in THF to afford hydro-2,2-tetramethylene-1-naphthol (mp 178-180 °C), and isomerized to 4a-(2-aminoethyl)-1,2,3,4,4a,9-hexahydro-6-methoxy-phenantrene i (mp 187 °C). 

A very simple synthesis of coumestrol (228) has been described by Kappe and coworkers (Scheme 46) (74ZN(B)292). It is based upon dehydrogenation of 4-hydroxy-3-phenyl-coumarins to coumestans (720PP233). A number of 2 -hydroxy 3-phenylcoumarins were oxidized with lead tetraacetate to the corresponding coumestans 3-(l-acetoxy-4-methoxy-2-oxo-3,5-cyclohexadienyl)coumarins were obtained as by-products (76BCJ1955). Coumes-tan itself (226) has been obtained by photolysis of the phenol ether (232), which is in turn available from 4-hydroxycoumarin (229) and (diacetoxyiodo)benzene (Scheme 47) (78CB3857) via an iodonium ylide (231). 

Benzene-induced shifts of methoxy protons have proved of value in the structural elucidation of various flavonoids (68JCS(C)2477). Additionally, information on the position of hydroxy groups follows from ASIS shown by the trimethylsilyl ethers of the flavonoids (72P409). Lanthanide shift reagents also contribute usefully to structural assignments, notably with biflavones (75JCS(P1)1563). 

Hydroxy-J-methoxy-5-w-propylbenzoic Acid (VI). Hydrogenation of methyl-(2-hydroxy-3-methoxy-5-allyl) benzoate (4) and subsequent saponification m.p., 119°-120.5°C. (benzene-w-hexane), yield = 80%. Elemental analysis calculated C, 62.85% H, 6.72% found C, 62.64% H, 6.80%. 

Hydroxy-J-methoxy-5-methylbenzal Acetone (XVII). According to the procedure reported for preparing 2-hydroxy-3-methoxybenzal acetone (13) m.p., 109°-110°C. (benzene-w-hexane), yield 66%. Elemental analysis calculated C, 69.88% H, 6.84% found C, 70.03% H, 6.79%. 

In practice, extrapolations of p fR in water have usually used the older acidity function based method, for example, for trityl,61,62 benzhydryl,63 or cyclopropenyl (6) cations.66,67 These older data include studies of protonation of aromatic molecules, such as pKSi = —1.70 for the azulenium ion 3,59 and Kresge s extensive measurements of the protonation of hydroxy- and methoxy-substituted benzenes.68 Some of these data have been replotted as p fR or pKa against XQ with only minor changes in values.25,52 However, for more unstable carbocations such as 2,4,6-trimethylbenzyl, there is a long extrapolation from concentrated acid solutions to water and the discrepancy is greater use of an acidity function in this case gives pA 2° = —17.5,61 compared with —16.3 (and m = 1.8) based on X0. Indeed because of limitations to the acidity of concentrated solutions of perchloric or sulfuric acid pICs of more weakly nucleophilic carbocations are not accessible from equilibrium measurements in these media. 

For phenol one can compare the effects of hydroxy and methoxy substituents. Scheme 19 shows effects of O-methyl substitution on pATas for protonation of a benzene ring containing one, two, and three hydroxy substituents. The pK s for di- and trihydroxy-substituted and methoxy-substituted benzenes were measured directly by Kresge et al.68 Again the stabilities of the hydroxy-substituted cations in water are consistently greater than methoxy. The importance of solvation in controlling these effects is demonstrated by the inversion of relative pK s of trihydroxy and trimethoxy benzene in concentrated solutions of perchloric acid.68 Thus the difference in p/fas is matched by a... 

Synthesis of podophyllotoxin (3.86) in cell culture of Linum album results in yields comparable to those of the most efficient tissue cultures of Podophyllum hexandrum. In order to further improve L. album cultures, Seidel et al. (2002) investigated the biosynthesis of podophyllotoxin (3.86). They fed a number of labeled compounds that to L. album cell cultures to identify which of these compounds could be used as precursors to podophyllotoxin. They determined that the substitution pattern on the benzene ring is critical. The substitution has to be either 3-methoxy, 4-hydroxy, as in ferulic acid (3.33), or, alternatively, 3,4-methylenedioxycinnamic acid (3.90) can serve as precursor. The precursor of podophyllotoxin in L. album appears to be deoxypodophyllotoxin (3.83), based on the higher level of isotope incorporation in the latter compound. This means that 7-hydroxymatairesinol, the precursors of 5-methoxypodophyllotoxin in L. flavum (Xia et al., 2000), is not a precursor of podophyllotoxin in L. album. 

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